CN109824033A - A kind of method of low cost preparation high thermal conductivity graphene film - Google Patents
A kind of method of low cost preparation high thermal conductivity graphene film Download PDFInfo
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Abstract
The invention discloses a kind of methods of low cost preparation high thermal conductivity graphene film.This method first disperses graphite powder, potassium permanganate in the concentrated sulfuric acid and phosphoric acid solution of 7:1-11:1, and graphite oxide suspension is made, and obtains graphene oxide dispersion by washing dispersion, filters at room temperature, graphene oxide film is prepared；It is placed in high-temperature resistance die, the graphene oxide film just restored；The graphene oxide film just restored is separately immersed in glucose, fructose, sucrose and the one or more solution of vitamin C, is warming up to 800-1000 DEG C, heat preservation was gradually cooling to room temperature after 50-70 minutes, obtained the graphene film of high thermal conductivity.Graphene film of the present invention is with a thickness of 10-50 microns and controllable, and room temperature is 1050-1550W m towards thermal coefficient‑1k‑1, tensile strength can reach 15-35MPa, and 100 180 ° of bendings are without breakage.
Description
Technical field
The present invention relates to graphene films, and in particular to a kind of method of low cost preparation high thermal conductivity graphene film, the height are led
Hot graphene film can be used for the fields such as aviation, mobile device.
Background technique
Most of traditional Heat Conduction Material be metal material, high mechanical strength, it is heat-resist but it is scarce have density it is big, it is thermally conductive
The disadvantages of rate is low, manufacturing cost is high, it is difficult to meet people to the needs of production and living.Nonmetallic materials are using graphene as representative
The research hotspot that there is a kind of carbon material the superior performance such as high thermal conductivity, corrosion-resistant to have become people.Root according to relevant report, at present
The graphene film thermal coefficient highest of high thermal conductivity has accomplished 3200W m-1k-1, using the prepared graphite of high temperature hot pressing reduction
The general 800-1800W m of its thermal coefficient of alkene film-1k-1, the high thermal conductivity graphite film of commercial type is substantially all by high temperature hot pressing
Processing, harsh working condition and high production cost limit their large-scale application.And use low-temp low-pressure reducing process
Handle graphene film prepared by (temperature is less than 2000 DEG C), destruction of the carbon dioxide of hot stripping process release to lamellar structure
Relatively strong, the fault of construction degree of gained RGO lamella is larger, and the heating conduction and mechanical performance of product are not able to satisfy wanting for people
It asks.Therefore, under the premise of guaranteeing graphene film high thermal conductivity, high-flexibility energy, reduce high thermal conductivity graphene film working condition and
Production cost is the major issue solved required for graphene film large-scale application.
Graphene is the two-dimensional atomic crystal being synthesized earliest, due to its with a series of outstanding performances and by
Extensive concern.Intensity, rigidity, the elasticity of graphene are high, have good mechanical property.In addition, graphene thermal conductance and electronics
Mobility is high, and band gap is adjustable.Many excellent performances concentrations, which appear in a kind of material, makes it in many applications
Other materials can be replaced, brings a series of technological break-throughs for related application field.The stone of one of macroscopic material as graphene
Black alkene film, it is especially prominent in terms of conduction heat transfer by its high thermal conductivity coefficient, however nowadays high thermal conductivity graphene film production process
High temperature hot pressing processing is generally used, and production process energy consumption height is not met with energy-saving and emission-reduction, and high, limitation is required production equipment
The large scale preparation of graphene film.Therefore one kind is studied with low-temp low-pressure, and guarantees the higher heating conduction of graphene film
Production technology with mechanical performance is a kind of development trend.
Summary of the invention
For overcome the deficiencies in the prior art, it is 1050-1550W that the present invention provides a kind of room temperatures towards thermal coefficient
m-1k-1, tensile strength is up to 15-35MPa, the side of the unabroken low cost preparation high thermal conductivity graphene film of 100 180 ° of bendings
Method has the advantage that preparation process temperature is low, pressure is low, easy to operate, pollution-free and inexpensive；Graphite prepared by the present invention
Alkene film need to only be handled by the low-temp low-pressure thermal reduction of 2 hours 800-1000 DEG C and 12-15MPa, and the high thermal conductivity of the prior art
Graphite film need to be handled by the high temperature and pressure thermal reduction of 3 hours 2800 DEG C and 200MPa or more.
The present invention prepares graphene oxide dispersion with improved Hummers method, then prepares oxygen using solution film formation
Graphite alkene film；Graphene oxide film after a hot pressing reduction treatment, be separately immersed in glucose, fructose, sucrose,
In the one or more solution of vitamin C, finally handle to obtain high thermal conductivity graphene film by secondary hot pressing reducing process.
The object of the invention is achieved through the following technical solutions:
A kind of method of low cost preparation high thermal conductivity graphene film, includes the following steps:
1) it oxidation processes: disperses graphite powder, potassium permanganate in the concentrated sulfuric acid and phosphoric acid solution of 7:1-11:1, in 40-
8-12 hour is stirred under the conditions of 60 DEG C, then cools to room temperature and hydrogen peroxide is added dropwise under ice-water bath and stirring condition to remove
Remaining potassium permanganate, obtains the graphite oxide suspension of glassy yellow；
2) washing dispersion: after the graphite oxide suspension stratification, outwelling supernatant, precipitates to graphite oxide
Dilute hydrochloric acid is added dropwise in object；Stratification adds dilute hydrochloric acid, repeated washing, to last time oxygen into sediment after outwelling supernatant again
Deionized water is added in graphite sediment, centrifugal treating outwells centrifuged supernatant, is added into remaining graphite oxide precipitating
Deionized water ultrasonic disperse 2-4 hours, is then charged into bag filter, is placed in deionized water a couple of days of dialysing, until dialysis
It is 6.5-7.0 that deionized water, which can't detect sulfate ion and pH value, obtains graphene oxide dispersion；
3) graphene oxide dispersion is filtered at room temperature, graphene oxide film is prepared；
4) graphene oxide film is placed in high-temperature resistance die, is warming up to 300-400 DEG C, in inert atmosphere
In, heat preservation was gradually cooling to room temperature after 50-70 minutes, the graphene oxide film just restored；
5) graphene oxide film of the first reduction is separately immersed in glucose, fructose, sucrose and vitamin C one
In kind or a variety of solution, after the graphene oxide film after immersion is then warming up to 800-1000 DEG C, heat preservation 50-70 minutes
It is gradually cooling to room temperature, is handled by Kun pressure, obtains the graphene film of high thermal conductivity.
To further realize the object of the invention, it is preferable that the mass ratio of the graphite powder, the concentrated sulfuric acid and potassium permanganate is
1:60-70:3-6。
Preferably, the concentrated sulfuric acid molar concentration is 15-18mol L-1, the concentrated phosphoric acid molar concentration is 16-
19mol L-1, the dilute hydrochloric acid molar concentration is 2.0-3.0mol L-1。
Preferably, the number of the repeated washing is 4-6 times；The revolving speed of the centrifugal treating is 4000-
6000rpm, time are 2-4 hours.
Preferably, the diameter 40-50mm of graphene oxide film described in step 3), with a thickness of 10-50 microns；Step 3)
The time of the suction filtration is 8-12h；The concentration 1.0-8.0mg/mL of step 2) graphene oxide dispersion stablizes storage 6
Month or more without precipitating generate.
Preferably, the concentration of step 5) glucose, fructose, sucrose and the one or more solution of vitamin C is 1-5mg/
mL。
Preferably, described in step 4) it is in an inert atmosphere high temperature process furnances or graphitization in inert atmosphere
In furnace: the inert gas includes argon gas or nitrogen.
It preferably, further include drying after the graphene oxide dispersion filters at room temperature, the drying is vacuum
It is dry.
Preferably, the graphene oxide film heating by after immersion is to put the graphene oxide film after impregnating
It is placed in boat and carries out；The high-temperature resistance die is graphite jig.
Preferably, the graphene film of the high thermal conductivity is with a thickness of 10-50 microns and controllable, and room temperature is towards thermal coefficient
1050~1550W m-1k-1, tensile strength 15-35MPa, 100 180 ° of bendings are without breakage.
Compared with the existing technology, the invention has the advantages that and the utility model has the advantages that
(1) present invention Hummers method preparation graphene oxide dispersion used improved is without using harmful nitrate
(such as sodium nitrate)；Graphene oxide dispersion is prepared by one-step oxidation process, it is easy to operate, it is easily prepared；Preparation
Graphene oxide dispersion can stablize storage 6 months or more without precipitating, the stannic oxide/graphene nano piece of a large amount of oxygen-containing functional groups
Between interact between stannic oxide/graphene nano piece and hydrone, can effectively maintain graphene oxide sheet material uniformly point
It dissipates, provides sufficient raw material guarantee for the subsequent graphene film for preparing.
(2) graphene film prepared by the present invention is with a thickness of 10-50 microns and controllable, is towards thermal coefficient at room temperature
1050~1550W m-1k-1, tensile strength 15-35MPa, without breakage, nothing is obviously fallen for 100 180 ° of reversed bendings or folding
Powder has good heat transfer property and mechanical performance.Current most of commercialized graphene film (such as Panasonic Japan PGS graphite
Alkene film, the scientific and technological graphene film of Changzhou carbon member etc.) all by 2800 DEG C and 200MPa or more of high temperature high pressure process, when film thickness is
At 40 microns, thermal coefficient is in 1100~1300W m-1k-1, 20~25MPa of tensile strength.And the present invention only need to be in 800-1000
Thermal coefficient 1053W m can be obtained compared with processing under lower pressure in DEG C lower mild 12-15MPa-1k-1, the stone of tensile strength 19MPa
Black alkene film.Compared with current commercialized graphene film, the heating conduction and mechanical performance of this product are in a slight decrease, but completely
People are able to satisfy to the production and living needs of high thermal conductivity graphene film, simple production process significantly reduces equipment requirement, the energy
Consumption is greatly reduced less, and prepared graphene film need to only pass through 2 hours 800-1000 DEG C and 12-15MPa low-temp low-pressures
Thermal reduction processing, and the high thermal conductivity graphite film of commercial type is substantially all by 2800 DEG C and 200MPa high temperature more than 2 hours
Hot high pressure reduction treatment, therefore this product production graphene film technique highly significant reduces the production cost of graphene film.
(3) the secondary hot pressing reducing process that the present invention uses, can be first in low temperature (300-400 DEG C) low pressure (2-5MPa) item
Most of oxygen-containing group in graphene oxide membrane is removed under part, then respectively in glucose, the sucrose, dimension that concentration is 1-5mg/ml
It is impregnated 3-7 days in one or more solution such as raw element C, finally in lower temperature (800-1000 DEG C), compared with low pressure (12-15MPa)
Under the conditions of, glucose, fructose, sucrose, vitamin C are generated active atoms of carbon by thermal decomposition and effectively repair graphene oxide membrane structure
Defect obtains surfacing and has the high-termal conductivity, excellent mechanical and the graphene film compared with low-density of metallic luster.Relative to
The prior art prepares commercial graphite film or graphene film under high temperature (2000-3000 DEG C) high pressure (200-300MPa) pressure to be had
The distinguishing features such as high energy-saving effect and milder working condition.
(4) graphene oxide membrane prepared by the present invention is separately immersed in glucose, fruit after a hot-pressing processing
In the one or more solution of sugar, sucrose, vitamin C, penetrated into after the long period impregnates graphene oxide membrane glucose,
The one or more molecules of fructose, sucrose, vitamin C decompose by 800-1000 DEG C of heat treatment and generate active atoms of carbon, effectively
Repair gap and the fault of construction of graphene film piece interlayer.Graphene film after reparation has more complete lamellar structure, leads
The passage of heat is more clear and more coherent, reduces phon scattering, improves the heating conduction and mechanical performance of graphene film entirety.
Detailed description of the invention
Fig. 1 is the effect picture after the GO dispersion liquid of the various concentration of 1 step 1) of embodiment preparation saves 1 day；
Fig. 2 is the effect picture after the GO dispersion liquid of the various concentration of 1 step 1) of embodiment preparation saves 180 days；
Fig. 3 is the SEM figure of gained graphene film before 1 step 4) of embodiment is repaired；
Fig. 4 is the SEM figure of gained graphene film after 1 step 4) of embodiment is repaired；
Fig. 5 is the TEM figure of graphene film before 1 step 4) of embodiment is repaired；
Fig. 6 is the TEM figure of graphene film after 1 step 4) of embodiment is repaired.
Specific embodiment
The present invention will be further described with reference to the examples below, but the present embodiment should not be understood as protecting the present invention
The limitation of range, those skilled in the art make some nonessential changes and adjustment according to the present invention, belong to the present invention
Protection scope.
The thermal coefficient of prepared film sample is calculated by formula λ=α ρ Cp, and wherein λ is the thermally conductive of sample
Coefficient (W m-1k-1), α is the thermal diffusion coefficient (mm of sample2s-1), ρ is density (the g cm of sample-3), Cp is the specific heat of sample
Hold (J g-1K-1)；Further, the measurement towards thermal diffusion coefficient of sample is shone using the laser with quick, accurate feature
Method, instrument are flicker method thermal conductivity factor instrument (447 NanoFlas of NETZSCH LFA), and test temperature is room temperature；Sample
Density is calculated by the quality and volume of sample；The specific heat capacity of sample by dynamic streaming differential scanning calorimeter (DSC,
NETZSCH DSC 204F1) measurement obtain, 25 DEG C of test temperature.Film sample is joined towards the specific test process of thermal coefficient
Examine document (Kong, Qing-Qiang, Liu Z, Gao, Jian-Guo, et al.Hierarchical Graphene-Carbon
Fiber Composite Paper as a Flexible Lateral Heat Spreader[J].Advanced
Functional Materials,2014,24(27):4222-4228；The preparation of the graphene-based film of Song Ningjing and mechanics and
Thermal property research university, [D] the Chinese Academy of Sciences, 2016).
Tensile strength refers to the drag for the maximum uniform plastic deformation that material can be born, the mechanical property to judgement material
Energy.The tensile strength of sample is tested using dynamic thermomechanical analysis apparatus (TA DMA Q800), prestressing force 0.01N, tensile speed
0.05%min-1.The tensile strength test of graphene film sample refers to Chinese Industrial Standards (CIS) number: ASTM F152-1995 (R2017).
Film sample is directly carried out 100 180 ° of bendings, radius of curvature minimum energy by bend test under no supporting condition
Reach 4.0 millimeters, no any damaged appearance.
Embodiment 1
A method of repairing graphene film defect, the specific steps are as follows:
(1) graphene oxide dispersion is prepared by improved Hummers method
Oxidation processes: the concentrated phosphoric acid of the concentrated sulfuric acid of 180mL and 20mL are mixed, and are kept for 35 DEG C of reaction system, and 2.0g is added
Graphite powder and 10g potassium permanganate.Then keep reaction solution temperature 50 C, stirring 12 hours after, be added 200 milliliters go from
The hydrogen peroxide solution of 5mL 30% is added dropwise under condition of ice bath to remove remaining potassium permanganate in sub- water, and it is bright to obtain solution presentation
The graphene oxide suspension of yellow；
Washing dispersion: the graphene oxide suspension stratification that will be obtained carefully outwells supernatant, adds into sediment
Enter 100 milliliters of 2.0mol L-1HCl, then stratification outwell supernatant and 100 milliliters of 2.0mol L are added-1HCl is repeated 3 times,
100 ml deionized waters are added into last time graphite oxide sediment, 4 hours are centrifuged under the conditions of 4000rpm, are outwelled
Centrifuged supernatant is added 150 ml deionized waters into remaining graphite oxide precipitating, ultrasonic disperse 3 hours, is then charged into
It analyses in bag, is placed in deionized water and dialyses 7 days, until the deionized water of dialysis can't detect sulfate ion and pH value is
7.0, obtain graphene oxide dispersion.Prepared graphene oxide dispersion has good water dispersible, by dilution
Concentration can reach 1-6mg/ml afterwards, stablizes and saves 6 months soilless stickings/precipitating generation.The prepared various concentration after dilution
GO dispersion liquid save 1 day and 180 days after effect picture such as Fig. 1 and Fig. 2, illustrate that there are the graphite oxides of a large amount of oxygen-containing functional groups
It interacts between stannic oxide/graphene nano piece and hydrone between alkene nanometer sheet, can effectively maintain graphene oxide sheet material
Evenly dispersed, the graphene oxide dispersion after long-time saves has no soilless sticking/precipitating and generates.
(2) vacuum filtration method is used, uniformly mixed graphene oxide dispersion is micro- with aperture 45 at 50 millimeters of diameter
Vacuum filter 6 hours on the cellulose mixture filter membrane (saliva is risen, water system filter membrane) of rice, then removes filter membrane and be put in 50 DEG C of vacuum drying
It is 2 hours dry in case, it tears cellulose mixture filter membrane and obtains graphene oxide based coextruded film；
(3) graphene oxide film is placed among graphite jig, applies 3MPa pressure, in the height of argon atmosphere protection
350 DEG C are warming up in warm tube furnace, heat preservation is gradually cooled to room temperature after sixty minutes, the graphene oxide membrane tentatively restored；
(4) graphene oxide membrane tentatively restored is placed in the glucose solution of 1.5mg/mL and impregnates five days, then
It puts and dries 2 hours in a vacuum drying oven, then remove and graphene oxide film is placed in boat, apply 13MPa pressure,
1000 DEG C are warming up in the graphitizing furnace of argon atmosphere protection, heat preservation was gradually cooling to room temperature after 3 hours, handled by Kun pressure
Obtain the graphene film of high thermal conductivity.
The graphene film for repairing front and back is as shown in Figure 3 and Figure 4 by scanning electron microscope (SEM) picture, can be with by Fig. 3
Find out that tomography is more in preprosthetic graphene film surface, passage of heat has some setbacks；Fig. 4 can be seen that the graphene film surface after repairing
Interior lamella marshalling, phantom is less, and whole passage of heat is more smooth, and heat conduction velocity is faster.
Repair front and back graphene film transmission electron microscope (TEM) as shown in Figure 5 and Figure 6, by Fig. 5 it can be seen that
The domain area of the film is smaller, and roughness is larger；Corresponding TEM phenogram 5 can be seen that lattice fringe arrangement is more chaotic,
And it is discontinuous, it is scattered during phonon transmission more.And Fig. 6 is the C-Gr film for adding glucose improvement, domain area is obvious
Increase, roughness is small, and for corresponding TEM phenogram 5 it can be seen that the film lattice striped is more apparent, marshalling illustrates grape
Sugar can effectively repair the defect of graphene nanometer sheet, improve sheet material domain area, and the passage of heat for improving film microstructure makes
It is more complete.
Graphene film after reparation has more complete lamellar structure, and passage of heat is more clear and more coherent, reduces phon scattering, mentions
The high heating conduction and mechanical performance of graphene film entirety.
After tested, graphene film obtained by the present embodiment is 1530W m towards thermal conductivity with a thickness of 16 microns-1k-1, tension
Intensity is 30MPa, and 100 180 ° of bendings are without breakage.
Material conducts heat rate and mechanical property manufactured in the present embodiment and the prior art (bibliography: Peng L, Xu Z,
Liu Z,et al.Ultrahigh Thermal Conductive yet Superflexible Graphene Films[J]
.Advanced Materials,2017,29(27)；Ding J,Rahman O U,Zhao H,et al.Hydroxylated
graphene-based flexible carbon film with ultrahigh electrical and thermal
Conductivity [J] .Nanotechnology, 2017,28.) compare, the graphene film that the present embodiment is prepared with a thickness of
16 microns, be 1530W m towards thermal conductivity-1k-1, tensile strength 30MPa；The graphene film of prior art preparation is with a thickness of 17
It is 1700W m towards thermal conductivity when micron-1k-1, tensile strength 38MPa.Thermal conductivity difference is only this product by comparison
170W m-1k-1, tensile strength difference is only 9MPa.Although people require the thermal conductivity of commercialized thermally conductive membrane material general
The higher the better, but thermal conductivity can reach 800W m-1k-1Above thermally conductive film material is able to satisfy the requirement of people substantially.Height is led
Hot graphene film can be used for the fields such as aviation, mobile device, such as Huawei Company in 2018 is proposed a entitled Huawei Mate
The mobile phone of 20X, the mobile phone use graphene heat dissipation film as heat dissipation film, and the heat-delivery surface being made into using graphene is radiated
Effect is far more than carbon nanotube, metal nanoparticle and other fillers.And this product simple production process, it is aobvious to equipment requirement
Writing reduces (not needing to be heated to 3000 DEG C of high-temperature production facility, it is only necessary to be heated to 1000 DEG C of production equipment), and the energy disappears
Consumption is greatly reduced less, and prepared graphene film only need to be by 800-1000 DEG C of 2 hours and 12-15MPa low-temp low-pressure heat
Reduction treatment, and the high thermal conductivity graphite film of commercial type is substantially all by 2800 DEG C and 200MPa high temperature height more than 2 hours
Thermal reduction processing is pressed, therefore this product production graphene film technique highly significant reduces the production cost of graphene film.
Embodiment 2
(1) graphene oxide dispersion is prepared by improved Hummers method
Oxidation processes: the concentrated phosphoric acid of the concentrated sulfuric acid of 180mL and 20mL are mixed, and are kept for 35 DEG C of reaction system, and 1.5g is added
Graphite powder and 9g potassium permanganate.Then keep reaction solution temperature 50 C, stirring 12 hours after, be added 200 milliliters go from
The hydrogen peroxide solution of 5mL 30% is added dropwise under condition of ice bath to remove remaining potassium permanganate in sub- water, and it is bright to obtain solution presentation
The graphene oxide suspension of yellow；
Washing dispersion: the graphene oxide suspension stratification that will be obtained carefully outwells supernatant, adds into sediment
Enter 100 milliliters of 3.0mol L-1HCl, then stratification outwell supernatant and 100 milliliters of 3.0mol L are added-1HCl is repeated 3 times,
100 ml deionized waters are added into last time graphite oxide sediment, 4 hours are centrifuged under the conditions of 4000rpm, are outwelled
Centrifuged supernatant is added 150 ml deionized waters into remaining graphite oxide precipitating, ultrasonic disperse 3 hours, is then charged into
It analyses in bag, is placed in deionized water and dialyses 7 days, until the deionized water of dialysis can't detect sulfate ion and pH value is
7.0, obtain graphene oxide dispersion.Prepared graphene oxide dispersion has good water dispersible, by dilution
Concentration can reach 1-6mg/ml afterwards, stablizes and saves 6 months soilless stickings/precipitating generation.The prepared various concentration after dilution
GO dispersion liquid save 1 day and 180 days after effect picture such as Fig. 1 and Fig. 2, illustrate the oxidation stone there are a large amount of oxygen-containing functional groups
It interacts between stannic oxide/graphene nano piece and hydrone between black alkene nanometer sheet, can effectively maintain graphene oxide sheet material
It is evenly dispersed, the graphene oxide dispersion after long-time saves has no soilless sticking/precipitating and generates.
(2) vacuum filtration method is used, uniformly mixed graphene oxide dispersion is micro- with aperture 45 at 50 millimeters of diameter
Vacuum filter 6 hours on the cellulose mixture filter membrane (saliva is risen, water system filter membrane) of rice, then removes filter membrane and be put in 50 DEG C of vacuum drying
It is 2 hours dry in case, it tears cellulose mixture filter membrane and obtains graphene oxide membrane；
(3) graphene oxide membrane is placed among graphite jig, applies 3MPa pressure, in the high temperature of argon atmosphere protection
350 DEG C are warming up in tube furnace, heat preservation was gradually cooled to room temperature after 1 hour, the graphene oxide membrane tentatively restored；
(4) graphene oxide film tentatively restored is placed in the glucose solution of 1.5mg/mL, solution is heated
It to 80 DEG C, then keeps temperature-resistant, impregnates 12 hours.The film after impregnating is taken out, it is small to dry 2 in a vacuum drying oven
When, it then removes and graphene oxide membrane is placed in boat, apply 13MPa pressure, in the graphitizing furnace of argon atmosphere protection
In be warming up to 1000 DEG C, heat preservation was gradually cooling to room temperature after 3 hours, handled to obtain the graphene film of high thermal conductivity by Kun pressure.It repairs
The graphene film of multiple front and back passes through scanning electron microscope (SEM) similar Fig. 3 and Fig. 4；Repair the transmission of the graphene film of front and back
The similar Fig. 5 and Fig. 6 of electron microscope (TEM).Graphene film after reparation has more complete lamellar structure, and passage of heat is more
Smoothness reduces phon scattering, improves the heating conduction and mechanical performance of graphene film entirety.
After tested, the present embodiment graphene film is 1230W m towards thermal conductivity with a thickness of 25 microns-1k-1, tensile strength
For 24MPa, 100 180 ° of bendings are without breakage.
Embodiment 3
(1) graphene oxide dispersion is prepared by the Hummers method of improvement
Oxidation processes: the concentrated phosphoric acid of the concentrated sulfuric acid of 180mL and 20mL are mixed, and are kept for 35 DEG C of reaction system, and 1.5g is added
Graphite powder and 10g potassium permanganate.Then keep reaction solution temperature 50 C, stirring 12 hours after, be added 200 milliliters go from
The hydrogen peroxide solution of 5mL 30% is added dropwise under condition of ice bath to remove remaining potassium permanganate in sub- water, and it is bright to obtain solution presentation
The graphene oxide suspension of yellow；
Washing dispersion: the graphene oxide suspension stratification that will be obtained carefully outwells supernatant, adds into sediment
Enter 100 milliliters of 2.5mol L-1HCl, then stratification outwell supernatant and 100 milliliters of 2.5mol L are added-1HCl is repeated 3 times,
100 ml deionized waters are added into last time graphite oxide sediment, 4 hours are centrifuged under the conditions of 4000rpm, are outwelled
Centrifuged supernatant is added 150 ml deionized waters into remaining graphite oxide precipitating, ultrasonic disperse 3 hours, is then charged into
It analyses in bag, is placed in deionized water and dialyses 7 days, until the deionized water of dialysis can't detect sulfate ion and pH value is
7.0, obtain graphene oxide dispersion.Prepared graphene oxide dispersion has good water dispersible, by dilution
Concentration can reach 1-6mg/ml afterwards, stablizes and saves 6 months soilless stickings/precipitating generation.The prepared various concentration after dilution
GO dispersion liquid save 1 day and 180 days after effect picture such as Fig. 1 and Fig. 2, illustrate the oxidation stone there are a large amount of oxygen-containing functional groups
It interacts between stannic oxide/graphene nano piece and hydrone between black alkene nanometer sheet, can effectively maintain graphene oxide sheet material
It is evenly dispersed, the graphene oxide dispersion after long-time saves has no soilless sticking/precipitating and generates.
(2) vacuum filtration method is used, uniformly mixed graphene oxide dispersion is micro- with aperture 45 at 50 millimeters of diameter
Vacuum filter 6 hours on the cellulose mixture filter membrane (saliva is risen, water system filter membrane) of rice, then removes filter membrane and be put in 50 DEG C of vacuum drying
It is 2 hours dry in case, it tears cellulose mixture filter membrane and obtains graphene oxide film；
(3) graphene oxide film is placed among graphite jig, applies 3MPa pressure, in the height of argon atmosphere protection
350 DEG C are warming up in warm tube furnace, heat preservation was gradually cooled to room temperature after 1 hour, the graphene oxide membrane tentatively restored；
(4) graphene oxide membrane tentatively restored is placed on the glucose and dimension that the 1:1 that concentration is 1.5mg/mL is mixed
It is impregnated in raw element C mixed solution five days, then dries 2 hours in a vacuum drying oven, then remove and put graphene oxide membrane
Be placed in boat, apply 10MPa pressure, be warming up to 1000 DEG C in the graphitizing furnace of argon atmosphere protection, after heat preservation 3 hours by
It is gradually cooled to room temperature, handles to obtain the graphene film of high thermal conductivity by Kun pressure.The graphene film for repairing front and back passes through scanning electron
The similar Fig. 3 and Fig. 4 of microscope (SEM)；Repair similar Fig. 5 and Fig. 6 of transmission electron microscope (TEM) of the graphene film of front and back.
Graphene film after reparation has more complete lamellar structure, and passage of heat is more clear and more coherent, reduces phon scattering, improves graphite
The heating conduction and mechanical performance of alkene film entirety.
After tested, the graphene-based laminated film of the present embodiment is 1053W m towards thermal conductivity with a thickness of 39 microns-1k-1,
Tensile strength is 19MPa, and 100 180 ° of bendings are without breakage.
Existing high thermal conductivity graphene film mostly uses high temperature (2000-3000 DEG C) high pressure (200-300MPa) to press when preparing
Power, operating condition is harsh, and energy consumption is high, high production cost (bibliography: Peng L, Xu Z, Liu Z, et al.Ultrahigh
Thermal Conductive yet Superflexible Graphene Films[J].Advanced Materials,
2017,29(27)；Ding J,Rahman O U,Zhao H,et al.Hydroxylated graphene-based
flexible carbon film with ultrahigh electrical and thermal conductivity[J]
.Nanotechnology,2017,28.).And traditional low-temp low-pressure reducing process is used to handle (temperature is less than 2000 DEG C) institute
The carbon dioxide of the graphene film of preparation, hot stripping process release is stronger to the destruction of lamellar structure, obtained RGO lamella
Fault of construction degree is larger, thermal conductivity and mechanical performance are generally 220-390W/mK and 10-15MPa, is not able to satisfy people couple
Requirement (the bibliography: Hou Z L, Song W L, Wang P, et al.Flexible Graphene- of graphene film
Graphene Composites of Superior Thermal and Electrical Transport Properties
[J].Acs Appl Mater Interfaces,2014,6(17):15026-15032.)。
A kind of method for reducing high thermal conductivity graphene film production cost of the present invention, have low temperature, low pressure, energy consumption compared with
Small feature, and effectively repair the defect of the graphene film, (graphene film that do not repair compared with the graphene film that do not repair
Thermal conductivity in 500-690W/mK) heating conduction is effectively improved, substantially meets people and want to the performance of highly heat-conductive material
It asks.
Present invention heat treatment temperature required compared with 2500-3000 DEG C of prior art processes temperature is lower, energy consumption
Less；Low pressure is that pressure used is 2-5MPa and 12-15MPa, and operation pressure 200-300MPa also has compared with prior art
The lower advantage of significant pressure, it is low for equipment requirements, reduce production cost；The present invention is due to low temperature, low pressure, the energy
Lesser advantage is consumed, working condition can be made milder in the upper one side of production, used equipment harsh conditions requirement
Less, the safety and reliability of operation are higher, operate also simpler, conveniently, and production cost substantially reduces；On the other hand, stone
The carbon atom reparation that black alkene film defect is generated by glucose, fructose, sucrose, the one or more molecule thermal decompositions of vitamin C, with
Graphene film (the thermal coefficient obtained without glucose, fructose, sucrose, the one or more solution immersion treatments of vitamin C
500~700W m-1k-1, 10~20MPa of tensile strength) and it compares, heating conduction and tensile strength have all obtained effective raising,
110%~120% and 50%~75% has been respectively increased, has met people and the performance of highly heat-conductive material is enough required.
Existing high thermal conductivity graphene film generally passes through the high temperature high pressure process of 2000-3000 DEG C He 200-300MPa, obtains
Thermal coefficient is generally in 1500W m in the graphene film surface arrived-1k-1Hereinafter, tensile strength is in 10~40MPa, production process
The high requirements on the equipment, energy consumption is big, production it is at high cost.
The present invention prepares graphene film only need to be by compared with low temperature (1000 DEG C) and compared with low pressure (12-15MPa) processing
Obtain the more superior graphene film of performance, it is with a thickness of 10-50 microns and controllable, in room temperature face thermal coefficient 1050~
1550W m-1k-1, tensile strength can reach 15-35MPa, and 100 180 ° of bendings are without breakage, and production process is to equipment requirement
Lower, energy consumption is few, and the cost of production is low.Material conducts heat rate and mechanical property prepared by the present invention and the prior art are (with reference to text
It offers: Peng L, Xu Z, Liu Z, et al.Ultrahigh Thermal Conductive yet Superflexible
Graphene Films[J].Advanced Materials,2017,29(27)；Ding J,Rahman O U,Zhao H,et
al.Hydroxylated graphene-based flexible carbon film with ultrahigh electrical
And thermal conductivity [J] .Nanotechnology, 2017,28.) it compares, the graphene film thickness being prepared
Degree is 16 microns, is 1530W m towards thermal conductivity-1k-1, tensile strength 30MPa；The graphene film thickness of prior art preparation
It is 1700W m towards thermal conductivity when being 17 microns-1k-1, tensile strength 38MPa.Thermal conductivity differs only this product by comparison
For 170W m-1k-1, tensile strength difference is only 9MPa.Although people require one to the thermal conductivity of commercialized thermally conductive membrane material
As the higher the better, but thermal conductivity can reach 800W m-1k-1Above thermally conductive film material is able to satisfy the requirement of people substantially.And
And this product simple production process, equipment requirement is significantly reduced and (does not need to be heated to 3000 DEG C of high-temperature production facility, only needs
It is heated to 1000 DEG C of production equipment), energy consumption is greatly reduced less, and prepared graphene film need to only pass through 2 hours
800-1000 DEG C and the thermal reduction of 12-15MPa low-temp low-pressure handle, and the high thermal conductivity graphite film of commercial type all passes through substantially
2800 DEG C more than 2 hours and 200MPa high temperature and pressure thermal reduction processing, therefore this product production graphene film technique is very aobvious
Write the production cost for reducing graphene film.
Graphene film of the present invention excellent combination property compared with prior art, although thermal coefficient and tensile strength are slightly less than
The graphene film of the prior art, but people are substantially met to the performance requirement of graphene film, it is often more important that the present invention is in temperature
More energy efficient under process conditions, the flexible light high thermal conductivity graphite alkene film of more inexpensive preparation has wide range of applications,
There is great application prospect in high-power, high heat flux density electronics industry and smart machine dissipation from electronic devices field.
Claims (10)
1. a kind of method of low cost preparation high thermal conductivity graphene film, it is characterised in that include the following steps:
1) it oxidation processes: disperses graphite powder, potassium permanganate in the concentrated sulfuric acid and phosphoric acid solution of 7:1-11:1, at 40-60 DEG C
Under the conditions of stir 8-12 hour, then cool to room temperature and under ice-water bath and stirring condition dropwise addition hydrogen peroxide to remove remnants
Potassium permanganate, obtain the graphite oxide suspension of glassy yellow；
2) washing dispersion: after the graphite oxide suspension stratification, supernatant is outwelled, into graphite oxide sediment
Dilute hydrochloric acid is added dropwise；Stratification adds dilute hydrochloric acid into sediment after outwelling supernatant again, and repeated washing aoxidizes stone to last time
Deionized water is added in black sediment, centrifugal treating outwells centrifuged supernatant, to remaining graphite oxide precipitating in be added go from
Sub- water ultrasonic disperse 2-4 hours, is then charged into bag filter, is placed in deionized water a couple of days of dialysing, until dialysis go from
It is 6.5-7.0 that sub- water, which can't detect sulfate ion and pH value, obtains graphene oxide dispersion；
3) graphene oxide dispersion is filtered at room temperature, graphene oxide film is prepared；
4) graphene oxide film is placed in high-temperature resistance die, is warming up to 300-400 DEG C, in an inert atmosphere,
Heat preservation was gradually cooling to room temperature after 50-70 minutes, the graphene oxide film just restored；
5) by the graphene oxide film of the first reduction be separately immersed in glucose, fructose, sucrose and vitamin C it is a kind of or
In a variety of solution, then the graphene oxide film after immersion is warming up to after 800-1000 DEG C, heat preservation 50-70 minutes gradually
It is cooled to room temperature, is handled by Kun pressure, obtain the graphene film of high thermal conductivity.
2. the method for low cost preparation high thermal conductivity graphene film according to claim 1, it is characterised in that: the graphite
The mass ratio of powder, the concentrated sulfuric acid and potassium permanganate is 1:60-70:3-6.
3. the method for low cost preparation high thermal conductivity graphene film according to claim 1, it is characterised in that: the dense sulphur
Sour molar concentration is 15-18mol L-1, the concentrated phosphoric acid molar concentration is 16-19mol L-1, the dilute hydrochloric acid mole is dense
Degree is 2.0-3.0mol L-1。
4. the method for low cost preparation high thermal conductivity graphene film according to claim 1, it is characterised in that: the repetition
The number of washing is 4-6 times；The revolving speed of the centrifugal treating is 4000-6000rpm, and the time is 2-4 hours.
5. the method for low cost preparation high thermal conductivity graphene film according to claim 1, it is characterised in that: step 3) is described
Graphene oxide film diameter 40-50mm, with a thickness of 10-50 microns；The time of suction filtration described in step 3) is 8-12h；
The concentration 1.0-8.0mg/mL of step 2) graphene oxide dispersion stablizes storage 6 months or more and generates without precipitating.
6. the method for low cost preparation high thermal conductivity graphene film according to claim 1, it is characterised in that: step 5) grape
Sugar, fructose, sucrose and the one or more solution of vitamin C concentration be 1-5mg/mL.
7. the method for low cost preparation high thermal conductivity graphene film according to claim 1, it is characterised in that: step 4) is described
Be in the high temperature process furnances or graphitizing furnace of inert atmosphere in an inert atmosphere: the inert gas includes argon
Gas or nitrogen.
8. the method for low cost preparation high thermal conductivity graphene film according to claim 1, it is characterised in that: the oxidation
Graphene dispersing solution further includes drying after filtering at room temperature, and the drying is vacuum drying.
9. the method for low cost preparation high thermal conductivity graphene film according to claim 1, it is characterised in that: described will leaching
Graphene oxide film heating after bubble is that the graphene oxide film after impregnating is placed in boat to carry out；The resistance to height
Warm mold is graphite jig.
10. the preparation method of high thermal conductivity graphene film according to claim 1, it is characterised in that: the high thermal conductivity
Graphene film is with a thickness of 10-50 microns and controllable, and room temperature is 1050~1550W m towards thermal coefficient-1k-1, tensile strength is
15-35MPa, 100 180 ° of bendings are without breakage.
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